1. Field of the Invention
The present invention relates to an organic light emitting display and a method of driving the same, and more particularly, to an organic light emitting display having improved display quality.
2. Discussion of the Background
Various thin and lightweight flat panel displays (FPD) have been developed to replace cathode ray tubes (CRT). Such FPDs include liquid crystal displays (LCD), field emission displays (FED), plasma display panels (PDP), and organic light emitting displays.
Generally, organic light emitting displays display images using organic light emitting diodes (OLED), which generate light by re-combination of electrons and holes. Organic light emitting displays typically have high response speed and low power consumption.
FIG. 1 shows a conventional organic light emitting display.
Referring to FIG. 1, the conventional organic light emitting display includes an image display unit 30 including pixels 40 formed at crossings of scan lines S1 to Sn and data lines D1 to Dm, a scan driver 10 for driving the scan lines S1 to Sn, a data driver 20 for driving the data lines D1 to Dm, and a timing controller 50 for controlling the scan and data drivers 10 and 20.
The scan driver 10 generates scan signals in response to scan driving control signals SCS from the timing controller 50 and sequentially supplies the scan signals to the scan lines S1 to Sn. The scan driver 10 also generates emission control signals in response to the scan driving control signals SCS and sequentially supplies the emission control signals to emission control lines E1 to En.
The data driver 20 generates data signals in response to data driving control signals DCS from the timing controller 50 and supplies the data signals to the data lines D1 to Dm. The data driver 20 supplies the data signals for one horizontal line to the data lines D1 to Dm every one horizontal period.
The timing controller 50 generates the data driving control signals DCS and the scan driving control signals SCS in response to input synchronizing signals. The timing controller 50 supplies the data driving control signals DCS to the data driver 20 and the scan driving control signals SCS to the scan driver 10. The timing controller 50 re-aligns data Data supplied from the outside and supplies the data Data to the data driver 20.
The image display unit 30 is coupled with a first power source ELVDD and a second power source ELVSS, which are supplied to the pixels 40. The pixels 40 display images corresponding to the data signals supplied thereto. The emission time of the pixels 40 is controlled by the emission control signals.
Here, the emission control signals are sequentially supplied to the first to nth emission control lines E1 to En together with the scan signals. Therefore, all of the pixels 40 included in the image display unit 30 emit light except for the short time during which the emission control signals are supplied.
However, the voltage of the first power source ELVDD may change in accordance with whether the pixels 40 emit light, that is, in accordance with the pattern and brightness of the images displayed by the image display unit 30. To be specific, the load applied to the first power source ELVDD in one frame varies with whether the pixels 40 emit light. Hence, when a large number of pixels 40 emit light in one frame, a large load is applied to the first power source ELVDD. On the other hand, when a small number of pixels 40 emit light in one frame, a small load is applied to the first power source ELVDD. Therefore, the voltage of the first power source ELVDD may change to correspond to the load. In this case, it may not be possible to display images with uniform brightness.